Many products have bodies or housings that include hollow cavities. As only some examples, automobiles, trucks, and other motor vehicles, as well as some consumer appliances, have hollow cavities formed between inner and outer panels, in pillars, or within their frame members that form their respective bodies or housings.
In particular, some structural members of automobile bodies have a variety of orifices, hollow posts, cavities, passages, and openings. Hollow cavities are often created in these products to reduce overall weight of the final product, as well as to reduce material costs. However, introducing hollow cavities into a structure involves tradeoffs. For example, introducing a hollow cavity may reduce the overall strength or energy-absorbing characteristics of a structural member. In addition, a hollow cavity may result in increased transmission of vibration or sound to other portions of the product.
It is known to use structural reinforcement materials to attempt to offset these and other tradeoffs. Some current reinforcers include an expansible material applied to a carrier, which typically is a molded component. The expansible material is expanded during the manufacture of the product, securing the reinforcer in place as the expanded material contacts the adjoining surface of the product. However, the expansible material in such reinforcers may not be securely joined to the carrier, leading to uneven or inadequate sealing. Moreover, expansion of the material may not reach every nook and cranny of an unusually or irregularly shaped carrier.
Additionally, some known expansible structural reinforcement materials can be sensitive to a heating process such as a “bake” process. The performance of such expansible materials is linked to the expansion rate, which depends upon the time and temperature of the heating.
Additionally, some known expansible structural reinforcement materials are thick, even before expansion. In such cases, the thickness of a pre-expansion material plus a gap between a reinforcement insert and a structural cavity can total about 8 to 10 mm to allow for e-coat flow and assembly tolerances. Structural reinforcement materials having reduced thicknesses can improve global system performance.
Thus, a need remains for an improved structural reinforcement material that alleviates at least some of these and other drawbacks.